Mozilla's controversial advertising program for Firefox is finally going mainstream after the non-profit first announced plans for the program in February. The official Firefox release now shows advertising on the new tab page when the browser is set to display Enhanced Tiles.

Mozilla's advertising looks no different than it did when we saw the tiles pop up in Firefox nightly builds in August. You have a number of tiles showing sites you've visited, as well as any tiles you've pinned to the new tab page. In addition, you'll see the advertising tiles with a largely unobtrusive, but still noticeable sponsored tag beneath them.

The first companies signed up to advertise in Firefox include Booking.com and CVS Health. The latter is a client of advertising firm Mindshare North America, which is partnering with Mozilla to deliver ads to Firefox.

The first ad I saw was for Citizenfour, the Edward Snowden documentary by Laura Poitras that has been appearing in pre-release builds of Firefox for several weeks.

The story behind the story: For years, Mozilla has led the charge against invasive online advertising and user tracking with add-ons such as Lightbeam. A big chunk of Mozilla's funding comes from a deal with Google that makes the company's search engine the default in Firefox. Hoping to offset its dependency on that deal, Mozilla is looking for other methods of funding—such as this new ad program.

You can opt out

Borrowing a phrase from the advertising industry that Mozilla typically opposes, the Firefox maker says it only collects user data in "aggregate form, meaning no data is personally identifiable." That aggregate information includes page impressions, clicks, and tile placement.

Kill ads by choosing the Classic or Blank new tab display options.

But Mozilla is still trying to stay true to its roots of a free and open web by making it easy to opt out of the new advertising scheme. All you have to do is go to a new tab page, click the settings cog you see in the upper right corner of the page, and select either Blank or Classic.

Blank mode will—surprise!—show you a completely blank page with no tiles whatsoever. Classic mode will show you history tiles with no advertising, according to Mozilla.

If you had opted in to Firefox's Do No Track option prior to the advertising tiles going live, Mozilla says you won't see the ads, either.

You can also just close that tile by hovering over it and clicking the "X" in the upper right corner. New ads will return to the browser later and closing ads won't stop Mozilla's tracking, but closing the tile is a quick fix if you don't want to bother messing with your settings.

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Ian is an independent writer based in Israel who has never met a tech subject he didn't like. He primarily covers Windows, PC and gaming hardware, video and music streaming services, social networks, and browsers. When he's not covering the news he's working on how-to tips for PC users, or tuning his eGPU setup.